Early stage prostate cancer is very common. However, current methods for diagnosis and treatment miss significant cancers in some men, and over-treat others with therapies that are expensive, lengthy, and have significant risks and morbidity. MRI is emerging as a promising method for revealing clinically significant prostate cancer, raising the provocative possibility of minimally invasive, focal, MR-guided therapy that would be more selective, safer, and quicker than current whole-gland radiotherapy and surgical procedures. The aims of this project are to develop minimally invasive biopsy and treatment methods for prostate cancer: 1. Design, testing and final fabrication of a new system for real-time, interactive, trans-perineal minimally invasive access to the prostate while the patient is in a 3T MRI scanner, using MRI-compatible robotic technology for passive remote needle manipulation, embedded miniature fiber optics and MR-tracking to sense needle shape and tip position, and integration with real-time MR scanning for automated visualization. 2. Clinical Trial of MRI-guided Trans-perineal biopsy of prostate targets, compared with subsequent TRUS-guided standard systematic 12-core biopsies (the gold standard) in 12 men with abnormal PSA levels. 3. Development and in vivo testing of MRI-compatible needle tip micro-robotics to dramatically increase physician control, including needle tip force sensing and rendering, and photonic needle tip steering. 4. Investigation of 3T methods for guiding and monitoring cryosurgery, including ultra-short TE 3D MR thermal mapping in frozen tissue, and advanced diffusion and MT-weighted images of acute cryo-injury. When complete, these technologies will be poised for future clinical trials assessing the utility of minimally invasive MRI-guided focal cryosurgery for treating early stage prostate cancer